The present invention relates to an image sensing apparatus utilizing a non-addition scanning type solid-state image sensing device.
Most of image sensing devices, such as a CCD, used in a domestic-use video camera, are composed of a great many number of photoelectric converters (pixels) arranged in two dimensions and a mechanism for sequentially transferring electric charges generated in the photoelectric converters. Upon transferring the electric charges, electric charges generated in the photoelectric converters in every other horizontal line are read out. Therefore, image signals of a half of the pixels in the image sensing device are outputted as image signals of each field in order to improve temporal scalability. As for an image sensing device whose surface is covered with a complementary color mosaic filter, electrical charges of pixels in two horizontal adjacent lines are added and read out upon transferring electric charges generated by the photoelectric converters (referred as "pixel addition scanning type", hereinafter), thereby improving temporal scalability as well as sensitivity.
The image signals obtained from the image sensing device as described above are interlaced signals, and a conventional domestic-use image sensing apparatus applies color processes, such as color reproduction, on the image signals from the image sensing device to generate video signals which conform to television standard, such as NTSC and PAL.
Further, a variety of automatic functions are provided to conventional domestic-use video cameras. Among those functions, there is a vibration blur correction function, which corrects blurs in an image due to vibration of the image sensing device when sensing the image, as a newly provided function. As for methods for correcting vibration blurs, they are roughly classified into two types: one is an electronic method which detects overall movement in a sensed image and controls an image output so as to cancel out the movement; and the other is an optical method which detects overall movement of a video camera by using an angular velocity sensor or an acceleration sensor, such as a gyro sensor, and controls a variable apical angle prism provided in an optical system in accordance with the detected result. In either method, processes are performed so as to achieve stable vibration blur correction in various situations for sensing a moving image. Panning compensation is one of the vibration blur correction methods. In this method, whether a detected movement is due to vibration of the camera or due to an intentional movement of the camera, such as panning and tilting, by an operator is determined. On the basis of the determination, the magnitude of vibration blur correction is changed. Thereby, vibration blurs are corrected as much as possible.
Meanwhile, there is a proposal to conventionally output image signals generated by a two dimensional image sensing device, as a moving image, to a television monitor of television standard, such as NTSC and PAL, as well as output the image signals to an information processing device, such as a computer and a printer, as a still image.
However, image signals which are generated in the conventional manner as described above do not have good vertical resolution since it is sacrificed for improving temporal scalability. Therefore, the quality of such images is inferiors to the quality of an image inputted by a stable image input device, such as a scanner.
If an image of an even-line field and an image of a successive odd-line field are combined together to make a frame image in order to avoid the aforesaid problem, when an object is moving, the combined frame image would not be a still image of high quality since the object looks differently when sensing an image of the even-line field and when sensing an image of the odd-line field. Further, in pixel addition scanning type image sensing device, image signals of a field are obtained by adding electric charges of pixels in two horizontal adjacent lines, vertical resolution is also deteriorated. Accordingly, the vertical resolution of a frame image does not improve by combining an image of an odd-line field and an image of a successive even-line field.
Accordingly, the first problem of an image sensing apparatus using the conventional image sensing device is that it is difficult to generate both video signals of various kinds of television standards and signals for a still image output medium.
Further, in a case of sensing a still image as described above, since the sensitivity and the dynamic range of the solid-state image sensing device are much lower and narrower than those of a silver halide film, the shutter speed of the image sensing device is necessarily set slower than that when using a silver halide film under the same image sensing conditions. Therefore, a high-performance vibration blur correction system is highly required for sensing a still image. However, when panning compensation for sensing a moving image is set to a vibration blur correction system, the performance of the vibration blur correction system is somewhat sacrificed, which results in an unsatisfactory vibration blur correction for a still image.
Accordingly, the second problem of the conventional technique is that satisfactory vibration blur correction function for sensing both a moving image and a still image has not been developed.